Switch assembly including rotary variable resistor

ABSTRACT

The assembly comprises a main or AC power source on-off switch, an on-off switch for a power source for preheating a picture tube, a switch for the heater circuit of the picture tube and a variable resistor for volume control, all of which may be controlled by a single operating shaft. When the operating shaft is pushed in and rotated to an extreme counterclockwise position, all of the AC power on-off switch, the power source switch for preheating and the switch for the heater circuit on-off are opened. When the operating shaft is rotated from an extreme counterclockwise position to a counterclockwise position, the power source switch for preheating is turned on and, while the shaft is rotatable in the clockwise direction the sound of a television receiver cannot be produced since the AC power and the heater circuit switches are still open at this stage. After the preheating switch is turned on and the shaft is pulled out, the AC and heater circuit switches are now on and the shaft is rotatable in the clockwise direction. As the shaft is turned towards the clockwise direction, the volume of a television receiver will increase. As the shaft is turned in the counterclockwise direction, the volume will decrease, and at the extreme counterclockwise rotational position the volume will be at its minimum and the shaft will be prevented from further rotation in the counterclockwise direction. When the shaft is pushed in, the AC power and heater circuit switches are off and picture and sound on the television receiver will fade away. At this stage, the preheater switch is still on and picture and sound will be produced immediately if the shaft is pulled out. When the shaft is further rotated toward the counterclockwise direction, the preheater switch will be turned off. At this shaft position the preheater switch is open and the shaft cannot be pulled out. The shaft can be pulled out only after it is turned in the clockwise direction and the preheater switch is on. After the preheater switch is turned on, push-pull operation of the shaft is possible at any position within a range of variable resistor rotation angle. While the shaft is pulled out it can be rotated freely and the volume of the television receiver can be readily increased and decreased. The preheater switch cannot be turned off while the shaft is pulled out. The switch can be turned off only when the shaft is pushed in and rotated to an extreme counterclockwise position.

United States Patent 1191 JA et al.

[ SWITCH ASSEMBLY INCLUDING ROTARY VARIABLE RESISTOR [75] Inventors: neim'raaaka rames? m Nakagawa, both of Osaka, Japan i 173] naigrieeinaaana Electric Relish-5T0.

Ltd., Osaka-fu, Japan [22] Filed: Apr. 2, 1973 [21] Appl. No.: 347,008

[30] Foreign Application Priority Data Primary Examiner-J. V. Truhe Assistant ExaminerDavid A. Tone ABSTRACT The assembly comprises a main or AC power source on-off switch, an on-off switch for a power source for preheating a picture tube, a switch for the heater circult of the picture tube and a variable resistor for volume control, all of which may be controlled by a single operating shaft. When the operating shaft is pushed in and rotated to an extreme counterclockwise position, all of the AC power on-off switch, the power 51 Oct. 8, 1974 source switch for preheating is turned on and, while the shaft is rotatable in the clockwise direction the sound of a television receiver cannot be produced since the AC power and the heater circuit switches are still open at this stage. After the preheating switch is turned on and the shaft is pulled out, the AC and heater circuit switches are now on and the shaft is rotatable in the clockwise direction. As the shaft is turned towards the clockwise direction, the volume of a television receiver will increase. As the shaft is turned in the counterclockwise direction, the volume will decrease, and at the extreme counterclockwise rotational position the volume will be at its minimum and the shaft will be prevented from further rotation in the counterclockwise direction. When the shaft is pushed in, the AC power and heater circuitswitches are off and picture and sound on the television receiver will fade away. At this stage, the preheater switch is still on and picture and sound will be produced immediately if the shaft is pulled out. When the shaft is further rotated toward the counterclockwise direction, the preheater switch will be turned off. At this shaft position the preheater switch is open and the shaft cannot be pulled out. The shaft can be pulled out only after it is turned in the clockwise direction and the preheater switch is on. After the preheater switch is turned on, push-pull operation of the shaft is possible at any position within a range of variable resistor rotation angle. While the shaft'is pulled out it can be rotated freely and the volume of the television receiver can be readily increased and decreased.

5 Claims, 15 Drawing Figures TO HEATER' SIIEH 3 0F 8 PATENTEDBET mm FIG. 5

PATENTED W 8 I 74 sum snr 8 FIG. 9

Pmmmm 3.840.838

sum ear 8 Pmmmm m 3.840.838

, sum m 8 FIG. l4 8 ASSEMBLY INCLUDING ROTARY VARIABLE RESISTOR BACKGROUND OF THE INVENTION The present invention relates to generally an improvement of a switch assembly including a rotary variable resistor, and more particularly a switch assembly including a rotary variable resistor for use in a preheat type television receiver including an AC power source on-off switch, an on-off switch for a power source for preheating a picture tube, and an on-off switch for a preheater circuit for the picture tube.

There has been successfully devised and demonstrated a preheat type television receiver of the type which'may produce the picture and sound immediately when an AC power source on-off switch is closed. In the television receivers of the type described, a switch of the type comprising an AC power source on-off switch and a switch or switches for preheating a picture tube have been used. These switches must be operatively coupled to each other so that the desired controls of the television receiver may be attained. They are generally complex both in mechanism and construction. That is, a switch for use with a preheat type television receiver must be so actuated that when only an AC power source on-off switch and a heater circuit on-off switch are closed and a preheating power source on-off switch is not closed, the cathode of a picture tube must not be preheated and that the preheating power source on-off switch must not be opened when the AC power source on-off switch and the heater circuit on-off switchare both closed. In other words, when the AC power source on-off switch and the heater circuit onoff switch are closed, the preheating power source switch must be also closed without fail.

SUMMARY OF THE INVENTION One of the objects of the present invention is to provide a power source on-off switch assembly including a rotary variable resistor for a preheat type television receiver. The switch assembly comprises an AC power source on-off switch, an on-off switch for a power source for preheating a picture tube, a switch for a heater circuit of the picture tube anda rotary variable resistor for volume control. These switches and the rotary variable resistor may be controlled by a single operating shaft. The AC power source on-off switch and the heater circuit on-off switch are closed when the operating shaft is pulled, but are opened when the operating shaft is pushed. The normally closed preheating SWITCH I power source on-off switch is opened by the rotation of the operating shaft to the extreme counterclockwise position. The operating shaft is prevented from being rotated to open the preheating power source switch when the operating shaft is pulled, but is permitted to open only when the operating shaft is pushed and the AC power source on-off switch and the heater circuit on-off switch are opened. Therefore the preheating power source switch can be opened only when both of the AC power source on-off switch and the heater circuit on-off switch are opened. When the operating shaft is not rotated to an extreme counterclockwise position, the preheating power source switch is normally closed. The resistance of the variable resistor is varied by the rotation of the operating shaft.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram used for the explanation of the functions of a switch assembly for use with a preheat type television receiver;

FIG. 2 is a front view of a first embodiment of the present invention;

FIG. 3 is a top view thereof;

FIG. 4 is a bottomview thereof;

FIG. 5 is a sectional view, on enlarged scale, taken along the line V-V of FIG. 3;

FIGS. 6 and 7 are sectional views taken along the lines VI--VI and VII-VII of FIG. 5;

FIG. 8 is a perspective view of an erratic operation preventive device;

FIG. 9 is a perspective exploded view of the device of FIG. 8;

FIG. 10 is a perspective view of a variation of the erratic operation preventive device shown in FIGS. 8 and FIGS. 11 and 12 are perspective and perspective exploded views of another variation of the erratic operation preventive device;

FIG. 13 is a front view of a second embodiment of the present invention;

FIG. 14- is a fragmentary vertical sectional view, on enlarged scale, of the embodiment of FIG. 13; and

FIG. 15 is a perspective view, on enlarged scale, of a connecting member used in the switch assembly shown in FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Principle, FIG. 1

First referring to FIG. 1 the required functions of a switch assembly of the type adapted for use with a preheat type television receiver will be described. The switch assembly generally comprises an AC on-off switch or main power source switch a, a preheat power source switch b, a transformer c, a fixed resistor d for limiting the preheating current, a switch e in a heater circuit of a picture tube (not shown), a plug f and a rectifier g for providing the DC power source. The heatercircuit switch e is operatively coupled to the AC or main on-off switch a as indicated by the dashed lines in such a manner that the switches a and e are both openedwhen the switch b is closed. When the switches a and e are simultaneously closed, a required heating current flows to the heater circuit of the picture tube.

The function of the circuit shown in FIG. 1 would not be satisfactory if the switches a and e are closed whereas the switch b has not been closed or if the switches a and e are closed whereas the switch b is opened. In other words the switch for a preheat type television receiver must function in such a manner that configuration (See FIG. 5) is mounted within the easing 3. The switch casing 6 is held in position by means of ears 5 extending from the upper ends of the upright side walls 4 of the casing 3. An upper or top cover 7 made of bakelite or the like and provided with an'operating shaft opening 8 is placed upon the top of the switch casing 6 and is securely held in position by means of the ears 5 in the manner well known in the art. A U-shaped actuating member 9, which may be fabricated by molding synthetic resin, is disposed within the switch casing 6 in such a manner that it may" be vertically slidable while being guided by a groove 10 formed in the side wall of the switch casing 6 as best shown in FIGS. 6 and 7. C-shaped contact members 1 1 and 12 provided with rivets l3 and 14 each of which serves as a contact are fixed to the side surfaces of the actuating member 9. Each of two U-shaped springs 15 has its one end fitted into a groove 16 formed inside the actuating member 9 and the other end fitted into an annular groove 17 formed in the operating shaft 1 as best shown in FIG. 5. Two pairs of switch terminals 18 and 19 are securely fixed to the top of the switch casing 6 by caulking, and contacts 20 and 21 (the latter being not shown) which are electrically coupled to the switch terminals 18 and 19 respectively are so disposed as to contact with or to be disconnected from the contacts 13 and 14 of the contact members 11 and 12. An insulating plate 22 is located at the bottom of the switch casing 6, and a washer 23 is fitted over the operating shaft 1 between the bearing 2 and the insulating plate 22. Thus a pushpull type switch 24 is constructed.

Above the push-pull type switch 24 is mounted an erratic operation preventive device generally indicated by 35, which generally comprises a base 28 and a stop 33 (See FIGS. 8 and 9). A support 25 and a shielding plate 27 are supported and securely held in position with the ears 5 extending from the upright side walls 4, and an intermediate bearing 26 is fitted into the center holes of the support 25 and the shield plate 27 and passes the operating shaft 1. The base 28 made of insulating material of the erratic operating preventive device 35 is mounted upon the shielding plate 27 and securely held in position by means of ears or legs 30 of a metal cover 29 which is mounted upon the base 28.

the periphery thereof and is securely fitted over the operating shaft 1 in such a manner that when the operating shaft 1 is pulled downwardly in the direction indicated by the arrow P and then rotated, the projection 34 of the stop 33 engages with the projection 32 of the base 28 so that no further rotation of the operating shaft 1 may be permitted, but when the operating shaft 1 is pushed upwardly, the projection 34 of the stop 33 is released from the projection 32 of the base 28 so that the rotation of the operating shaft l'may be permitted.

Above the erratic operation preventive device 35 is mounted a rotary variable resistor generally indicated by 47. On the top of the cover 29 is mounted an intermediate bearing 36 around which are fitted a shielding plate 37 and provided with a center hole through which extends the operation shaft 1. A horseshoe-shaped resistance element 39 is formed upon the base 38 made of insulating material and has both ends thereof electrically connected to terminals 40 (see FIGS. 3 and 4). A contact 42 is fixed to the base 38 by caulking an intermediate terminal 41. A cup-shaped metallic cover 43 is mounted on the base 38 and joined together with the base 38 to the cover 29 of the erratic operation preventive device 35 by means of legs 44 (see FIG. 2). A both sides fiatted hole 64 of a wiper arm holder 45 made of an insulating material is slidably engaged with an upper end portion of the operating shaft 1, and a wiper arm 46 which makes a sliding contact with the resistance'element 39 and the contact 42 is fixed to the undersurface of the wiper arm holder 45.

A center hole 60 is provided in the wiper arm holder 45 which engages rotatably with an extruded wiper arm holder 61 provided at the bottom of metal cover 43. A wiper arm holder rotation stop 62 a fourth projection is provided at the inside periphery of metal cover 43 and abuts on a radially extended portion 63 a third projectionof a wiper arm holder 45 when the shaft 1 is pushed-in in the direction opposite to that indicated by arrow P and projection 34 of stop 33 disengaged from projection 32 of the base 28.

Therefore, stop 62 and extended portion 63 serve to stop or limit the rotation of wiper arm holder 45 and shaft 1 when the shaft 1 is pushed-in and projection 32 of base 28 and projection 34 of stop 33 serve to stop or limit rotation of wiper arm holder 45 and shaft 1 when the shaft 1 is pulled-out as indicated by arrow P.

While the operating shaft 1 is pulled-out, if the projections 32 and 34 are destroyed by applying to the shaft 1 an extremely large rotation torque, then stop 62 and extended portion 63 work to stop the rotation of the shaft 1.

A rotary switch generally indicated by 52 is mounted upon the variable resistor 47. A switch casing 48 is mounted on the top of the cover 43 of the variable resistor 47, and an actuator 49 which is located within the casing 48 extends into the cover 43 of the variable resistor 47 so as to engage with a fifth projection 50 formed integral with the wiper arm holder 45. Two switch terminals 51 are caulked to the casing 48 and insulated from the upper surface of the cover 43 and electrically connected to fixed contacts (not shown) which are disposed within the casing 48 and closed or opened by the actuator 49.

When the rotary switch 52 is opened or off, the projection 34 of the stop 33 is located immediately above the projection 32 of the stop 33 of the erratic operation preventive device 35 so that when the operating shaft 1 is pulled in the direction indicated by the arrow P, the projection 34 abuts on the upper surface of the projection 32. As a result the push-pull switch 24 is prevented from being closed by error.

Next the mode of operation will be described. When the operating shaft 1 is pulled in the direction indicated by the arrow P as shown in FIG. 5, the actuator 9 of the switch 24 is caused to move upwardly in the direction opposite to that indicated by the arrow P under the forces of the U-shaped springs 15 so that the contacts 13 and 14 of the contact members 11 and 12 fixed to the actuator 9 contact the contacts 20'and 21 connected to the switch terminals 18 and 19. As a result the terminals 18 and 19 are electrically connected.

When the operating shaft 1 is rotated from the position shown in FIG. 5, the stop 33 of the erratic operation preventive device is also rotated so that the projection 34 of the stop 33 engages the projection 32 of the base 28. As a result the rotation of the operating shaft 1 is stopped. That is, the angle of rotation of the operating shaft 1 is limited. The wiper arm holder 45 of the variable resistor 47 is also rotated as the operating shaft 1 is rotated so that the wiper 46 slides over the resistance element 39. Since the contact 42 is always engaged by the wiper 46, the resistance between the wiper terminal 41 and one of the terminals is varied. When the projection 34 of the stop 33 engages the projection 32 of the base 28, the projection 50 of the wiper arm holder will not actuate the actuator 49 of the rotary switch 52. The actuator 49 of the rotary switch 52 is actuated by the projection of the wiper arm holder 45 only when the shaft 1 is pushed-in and rotated to the position where the projection 34 of the stop 33 comes immediately above the projection 32 of the base 28.

When the operating shaft 1 is pushed in the direction opposite to that indicatedby the arrow P, the actuator 9 is caused to move downwardly under the forces of the U-shaped springs 15 so that the electrical connections between the switch terminals 18 and 19 are opened. That is, the switch 24 is opened. The stop 33 is moved upwardly away from the base 28 so that the projection 34 will not engage with the projection 32 when the operating shaft 1 is rotated. When the operating shaft 1 is rotated to an extreme counterclockwise position, the actuator 49 is actuated by the projection 50 of the wiper holder 45 so that the contactsin the switch cas- 3 ing 48 are opened. That is the rotary switch terminals 51 are electrically disconnected.

When the operating shaft 1 is pulled in the direction indicated by the arrow P when the rotary switch S2 is off, the projection 34 of the stop 33 engages with projection 32. As a result the operating shaft 1 cannot be pulled in the direction indicated by the arrow P, so that the push-pull switch 24 cannot be closed and remains in opened position. However when the operating shaft 1 is rotated, the projection 34 of the stop 33 is moved away from the projection 32 of the base 28 so that the operating shaft 1 may be pulled in the direction P and the switch 24 may be closed. Even when the operating shaft 1 is pushed in the direction opposite to that indi cated by the arrow P, the resistance between the wiper terminal 41 and one of the terminals 40 of the variable resistor 47 may be varied.

The switch according to the present invention may be used as the switch assembly whose circuit diagram is shown in FIG. 1. The push-pull switch 24 is used as the AC power source on-off switch a; the rotary switch 52 is used as the switch b; and the switch 24 is also used as the switch e. That is, the switch terminals 18 of the push-pull switch 24 are used as the switch a whereas the switch terminals 19 are used as the switch e. When the switch 52, that is the switch b is off, the switch terminals 18 (the switch a) and the switch terminals 19 (switch e) will not be closed at all, but when the switch 52 is closed the switch terminals 18 and 19, that is the switches a and e may be closed. As long as the switch terminals 18 and 19 are closed, the switch 52 will not be opened. The switch 52 may be opened only after the switch terminals 18 and 19 are opened.

In the first embodiment, the pushpull switch 24 has been described as being closed when the operating shaft 1 is pulled, but it will be understood that the first embodiment may be modified so that the switch 24 may be closed when the operating shaft 1 is pushed. In this case the erratic operation preventive device must be so modified that the rotary switch 52 is not actuated when the operating shaft 1 is pushed. but is opened when the operating shaft 1 is pulled. Furthermore when the switch 52 is off, the erratic operation preventive device 35 must prevent the operating shaft 1 from being pushed. The pushpull switch 24 and the rotary switch 52 may be also modified in construction.

As described hereinbefore the pushpull switch cannot be actuated when the rotary switch is off and when the pushpull switch is on, the rotary switch cannot be made opened or off. The rotary switch is on when the pushpull switch is on. When the switch of the present invention is used in a preheat type television receiver, the erratic operation can be completely eliminated. That is, the problem that the preheat switch is not closed when the power source switch is closed may be overcome. The switch of the present invention is simple in construction and inexpensive to fabricate.

Variation, FIG. 10

A variation of an erratic operation preventive device 35 is shown in FIG. 10. The projection 32 has a sloping surface 32a so that when the operating shaft 1 is rotated in the clockwise direction, the projection 34 of the stop 33 may easily ride over the sloping surface 32a. As a result the operating shaft 1 is automatically pushed into the switch as it is rotated so that the contacts 11 and 12 are moved away from the contacts 13 and 14. That is, the contacts are opened without fail before the rotary switch 52 is opened.

Variation, FIGS. 11 and 12 Another variation of the erratic operation preventive device 35 shown in FIGS. 11 and 12 is substantially similar to the device 35 shown in FIG. 10 except that the projection 34 of the stop 33 is also provided with a sloping peripheral surface 34a which makes contact with the projection 32. Therefore the rotation as well as the push-in operation of the operating shaft 1 may be much facilitated.

Second Embodiment, FIGS. 13 15 A second embodiment shown in FIGS. 13 15 is substantially similar to the first embodiment described above except that instead of the support, the shielding plate 27, the base 28 and the metal cover 29 of the erratic operation preventive device 35, a connecting member 101 is used.

The connecting member 101 is fabricated by die casting and mounted at the top of the switch casing 6 together with the top cover 7 by means of the legs 5 which are extended from the upright side wall 4 of the casing 3 and pressed against the connecting member 101.

As best shown in FIG. 15, the connecting member 101 has a hollow space and a closed bottom which is provided with a opening 102 through which is extended the operating shaft 1. Inside the circular hollow space of the connecting member 101 a projection 103 integral with the inner wall thereof is formed. The projection 103 corresponds to the projection 34 of the stop 33 of the erratic operation preventive device 35 of the first embodiment and serves not only to limit the rotation but also to prevent the vertical movement of the operating shaft 1. At the top surface of the connecting member 101 a pair of projections 104 in diametrically opposed relation are formed. The projections 104 are fitted into mating holes formed in the undersurface of the base 38 of the variable resistor 47 so that the latter may be securely held in position when assembled.

According to the second embodiment, there are advantages that the assembly is simple and the fabrication cost is inexpensive because the one-piece connecting member 101 is used instead of the cover 25, the shielding plate 27, the base 28 and the metal cover 29 and that the joint between the pushpull switch 24 and the base of the rotary variable resistor 47 may be ensured.

What is claimed is:

l. A switch assembly including a rotary variable resistor comprising:

a. an operating shaft,

b. a pushpull switch in a switch casing adapted to be closed in response to axial movement of said operating shaft in one direction and opened in response to axial movement of said operating shaft in the opposite direction,

c. stop means securely fitted over said operating shaft and provided with first projection means,

d. second projection means adapted to engage said first projection means of said stop means when said operating shaft is moved in said one axial direction thereof so as to close said push-pull switch and is rotated to a position where said second projection means is located, thereby limiting the rotation of said operating shaft, said second projection means being also adapted to permit the rotation of said operating shaft when saidoperating shaft is moved in said other axial direction thereby opening said push-pull switch, and further adapted to prevent the further movement of said operating shaft in said one axial direction thereof when said operating shaft is moved in said other axial direction and rotated to the location where said first projection means is immediately above said second projection means,

e. the rotary variable resistor on a base plate, whose wiper arm is rotatable in unison with said operating shaft to vary its resistance, and

f. a rotary switch adapted to be opened by the rotation of a holder for said wiper arm of said rotary variable resistor only when'said operating shaft is moved in said other axial direction thereof and thereafter rotated to said location where'said first projection means is positioned above said projection means.

2. An electrical control assembly as defined in claim 1 wherein one end of said second projection means which first makes contact with said first projection means is upwardly sloped.

3. An electrical control assembly as defined in claim 1 wherein one end of said second projection means which first makes contact with said first projection means is upwardly sloped, and

one end of said first projection means which first makes contact with said one end of said second projection means is sloped downwardly.

4. An electrical control assembly as defined in claim 1 wherein said base and said second projection means are formed integrally with said substantially cylindrical housing.

5. An electrical control assembly as defined in claim 1 wherein said second projection means is formed integrally with a base which is in turn securely fixed to a casing of said pushpull switch. 

1. A switch assembly including a rotary variable resistor comprising: a. an operating shaft, b. a pushpull switch in a switch casing adapted to be closed in response to axial movement of said operating shaft in one direction and opened in response to axial movement of said operating shaft in the opposite direction, c. stop means securely fitted over said operating shaft and provided with first projection means, d. second projection means adapted to engage said first projection means of said stop means when said operating shaft is moved in said one axial direction thereof so as to close said push-pull switch and is rotated to a position where said second projection means is located, thereby limiting the rotation of said operating shaft, said second projection means being also adapted to permit the rotation of said operating shaft when said operating shaft is moved in said other axial direction thereby opening said push-pull switch, and further adapted to prevent the further movement of said operating shaft in said one axial direction thereof when said operating shaft is moved in said other axial direction and rotated to the location where said first projection means is immediately above said second projection means, e. the rotary variable resistor on a base plate, whose wiper arm is rotatable in unison with said operating shaft to vary its resistance, and f. a rotary switch adapted to be opened by the rotation of a holder for said wiper arm of said rotary variable resistor only when said operating shaft is moved in said other axial direction thereof and thereafter rotated to said location where said first projection means is positioned above said projection means.
 2. An electrical control assembly as defined in claim 1 wherein one end of said second projection means which first makes contact with said first projection means is upwardly sloped.
 3. An electrical control assembly as defined in claim 1 wherein one end of said second projection means which first makes contact with said first projection means is upwardly sloped, and one end of said first projection means which first makes contact with said one end of said second projection means is sloped downwardly.
 4. An electrical control assembly as defined in claim 1 wherein said base and said second projection means are formed integrally with said substantially cylindrical housing.
 5. An electrical control assembly as defined in claim 1 wherein said second projection means is formed integrally with a base which is in turn securely fixed to a casing of said pushpull switch. 